JPH04199592A - Manufacture of copper-foiled circuit board - Google Patents

Abstract

PURPOSE:To reduce a difference in etching amount with positions in the right and left faces and the to and bottom of a substrate by casting substrates with an etcher equipped with the carrier division made up of a roller zone and support rollers and the nozzle division by treating them under specified conditions. CONSTITUTION:Substrates are introduced in upright into etching baths 10, 20 driven by feed driving jigs 11, 21, 12, 22, 13, counterposed almost overall on the right and left sides with the axis as the vertical direction, and carried by a carrier made up of a roller zone equipped with rollers 14, 24 arranged each in the carriage direction to sandwich and feed substrates and substrate support rollers 17 driven by drivers 15, 25, 16, 26. During this carriage, a prescribed etchant 5 is sprayed from spray nozzles 18, 28 provided on both sides. It etches the whole copper foil at a sped of 0.01-0.4mum/sec to make 10-80% of an original thickness of copper foil remain, thereby adjusting dispersion in the thickness of the remaining copper foil within + or -1.0mum. This process can reduce thickness dispersion with place.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement in a method for manufacturing a thin copper foil-clad circuit board by etching, in which the copper foil-clad circuit board is conveyed vertically. By etching, thin copper foil-clad circuit boards with excellent dimensional accuracy can be manufactured stably and with high productivity by greatly reducing variations in etching accuracy depending on location.

[Conventional technology and its problems]

The inventors of the present application previously published Japanese Patent Application Publication No. 2-50189,
0, -25089, -22896, -22887, same 2
-Proposed a manufacturing method for thin copper foil-clad circuit boards such as 97688.

It is understood that thin copper-clad circuit boards are more effective in producing printed wiring boards with finer patterns (=fine patterns), and in order to produce more advanced fine patterns, the thickness of There is a need for something with even smaller variations.

When this purpose is carried out using a conventional horizontal etching machine, problems occur such as the balance between the etching speed of the top and bottom surfaces, variations in the thickness within the top surface, and insufficient etching, especially in the central part. However, it is inconvenient to use large substrates or mass-produce.

As a solution to this problem, Japanese Patent Application Laid-open No. 2-97688 was proposed, but it had the disadvantage of requiring the use of a conveying jig.

[Means to solve the problem]

The present invention was developed as a result of extensive research into a method for manufacturing thin copper foil-clad circuit boards with high productivity that solves the above-mentioned disadvantages.
The present invention has been achieved.

That is, the present invention is a thin copper film in which a copper foil-clad circuit board (a) manufactured from a copper foil with an average thickness of 12 mm or more and an electrical insulator is transported upright and the entire surface is etched using a copper etching solution. A method for manufacturing a foil-clad circuit board, which includes a feeding drive tool (1) provided at the upper end along the conveyance direction, and driven by the drive tool (1), and almost entirely on both left and right sides below the feeding drive tool (1). A roller section that sandwiches and conveys the substrate (a), comprising a large number of rollers (4) arranged opposite to each other with their axes in the vertical direction, each along the conveyance direction and arranged on the axis; (4) A conveyance section (A) for the substrate (a) consisting of at least a supporting roller (7) provided at the lower end of the substrate, and a large number of spray nozzles (8) provided on both left and right sides along the conveyance direction. ) consists of a nozzle part (
B) The substrate (a) is placed in an etching apparatus having the following, and the entire surface of the copper foil is etched at a speed of 0.01 to 0.4 Arn/sec to a thickness of 10 to 80% of the original thickness of the copper foil. The variation in the thickness of the remaining copper foil relative to the desired thickness is ±
A method for manufacturing a thin copper foil-clad circuit board with a thickness within 1.0ρ,
The support roller (7) is driven by the drive shaft (5) at the same feed speed as that of the roller (4), and the etching zone having the nozzle portion (B) is formed in two stages. the spray nozzle (
8) The copper etching solution supplied in step 8) must be filtered in advance, and the etching may be carried out at an etching speed of 0.01 to 0.347 seconds and a spray pressure of 0.
The predetermined condition is selected from the range of 3 to 1.3 kg/cat.

Further, the copper etching solution used in the present invention contains hydrogen peroxide 1.5 to 4 w/v%, sulfuric acid 3 to 7 w/v%, copper 10 to
100g#! and the hydrogen peroxide, sulfuric acid and copper concentrations are controlled within ±1.0% of the specified concentration, and the temperature is 25 to 60°C.
It is controlled within ±1.0deg,
Furthermore, the copper etching solution contains no alcohol as an auxiliary agent.
．． The copper etching solution contains 0.25 to 3 mol/8 chloride of 1 to 5 w/v%;
1 to 5 mol/l of hydrochloric acid, the hydrochloric acid concentration is controlled within ±0.3 mol/1 of the predetermined concentration, and the temperature is 25 mol/l.
±5. at ~55°C. This is a method for manufacturing thin copper foil-clad circuit boards by controlling the temperature within 100 degrees.

The configuration of the present invention will be explained below.

First, the copper foil-clad circuit board (a) manufactured from the copper foil and electrical insulator of the present invention has an average thickness of 12p or more, and a variation in thickness with respect to the average thickness of ±1. There is no particular limitation as long as it uses copper foil within OJa, and various commercially available products used for electronic and electrical materials can be used, including single-sided or double-sided copper-clad films, sheets, and fiber-reinforced products. These include insulating resin laminates, metal core laminates, and multilayer shield plates with printed wiring networks formed on the inner layer.

Here, the electrical insulating layer is made of a film or sheet of polyimide resin, polyester resin, etc., thermosetting resin or heat-resistant thermoplastic resin, and glass (E glass, D glass, S glass, quartz glass, etc.) , ceramics (
alumina, boron nitride, etc.), fully aromatic polyamide,
Prepreg is made by combining a porous film or sheet-like reinforcing base material using fibers, chops, etc. made of one or more types of polyimide, semi-carbon, fluorine resin, and other heat-resistant engineering plastics. or those made by coating an iron, aluminum plate, etc. with an insulating adhesive or adhesive film. In addition, the method for manufacturing copper-clad laminates or sheets using thin copper foil of 12 to 16 mm is as follows:
A preferred method is to insert a sheet of about 40 to 100 mm thick, such as aluminum foil, which has a higher coefficient of thermal expansion than the copper foil, between the copper foil and the mirror plate, and perform lamination molding.

Further, the surface of the copper foil of the copper-clad circuit board (a) used in the present invention must be clean, that is, "dust" that acts as an etching resist has been removed. If such "dust", especially resin powder, is attached, the copper foil in that area is not etched and remains, forming protrusions. Therefore, in order to remove such "dust", it is more preferable to use a material that has been subjected to mechanical polishing, treatment with a desmear treatment liquid, or the like.

The copper foil-clad circuit board (a) described above is introduced into a vertical etching machine and etched under predetermined conditions to produce the thin copper-clad circuit board of the present invention.

The copper etching solution of the present invention used for etching the copper foil-clad circuit board (a) is an aqueous solution containing hydrogen peroxide/sulfuric acid, copper chloride, persulfate, iron chloride, or the like as a main ingredient. Compared to the etching solution used for etching, methods of keeping the concentration of etching components low, methods of keeping the temperature low, methods of making the amount of contact of the supplied etching solution on the copper foil surface uniform and small (in the case of the spray method, The etching rate is reduced by lowering the spray pressure) or by appropriately combining the above methods.
in the range of μm/sec, preferably 0. The predetermined etching rate is selected from the range of ~0.3 μR/sec, more preferably from 0.03 to 0.2 us/sec, particularly from 0.05 to 0.11 μR/sec.

In the present invention, peroxide S/sulfuric acid type and copper chloride type etching solutions are suitable. In addition, the etching speed is 0.41
．． If the etching speed is faster than aA/sec, the degree of progress of etching will vary due to a slight difference in etching processing time, and not only will the difference from the desired thickness become large, but there will also be a tendency for the thickness to vary widely depending on the location. The variation width for thickness is ±1. This is not preferable because it becomes difficult to keep it within 0-.

Also, the etching speed is 0. If it is slower than -7 seconds, etching takes a long time and is not practical.

The spray pressure used for spray etching is in the range of 0.3 to 1.3 kg/caf, preferably in the range of 0.3 to 0.8 kg/caf, particularly in the range of 0.4 to 1.3 kg/caf.
A range of O56 kg/cfIl is preferred. This preferred spray pressure range is smaller than that used in normal pattern etching, and is also smaller than that used when a horizontal etching machine is used for full surface etching. By using a vertical type, it is possible to apply such a low spray pressure, so even if the substrate is as thin as 0.1 ml Tl, there is virtually no ``flapping'' of the substrate due to the spray during processing. , which enables more homogeneous etching.

In the case of a suitable hydrogen peroxide/sulfuric acid based copper etching solution used for the above etching, hydrogen peroxide is 1.5 to 4 w/v%.
, sulfuric acid 3-7 w/v%, temperature 25-50°C, copper concentration 10
~100g#, optionally additives such as hydrogen peroxide stabilizers, copper brighteners - monohydric alcohols such as methanol, ethanol, propatool, butanol; ethylene glycol, propylene glycol, phthanediol, Examples include dihydric alcohols such as bentanediol; alcohols containing trihydric or higher hydric alcohols such as glycerin and pentaerythritol. In addition, in the case of copper chloride, cupric chloride is 0.5 to 2 mol/j! , hydrochloric acid 1-3
．． An aqueous solution having a concentration of 6 mol/l and a temperature of 25 to 55° C. is preferred, especially when used directly on site. A further example is a method of treating with the cupric chloride-based etching solution described above, followed by treatment with the hydrogen peroxide/sulfuric acid-based copper etching solution or chemical polishing solution.

The copper foil-clad circuit board (a) described above is etched using a copper etching solution while being conveyed vertically to produce the thin copper foil-clad circuit board of the present invention.

In order to facilitate understanding of the etching apparatus of the present invention, an example thereof will first be described with reference to the accompanying drawings.

FIG. 1 is a plan view of a vertical etching apparatus used in the present invention, and FIG. 2 is a side view of the same.

In the apparatus shown in Figure 1.2, a copper foil-clad circuit board (a
) is the etching tank (10, 20) standing from the left side of the drawing.
The feeding drive tool (11, 2
1, 12, 22, 13), and are installed below them on both the left and right sides, facing each other almost entirely with their axes in the vertical direction.
A large number of rollers (
14, 24) for sandwiching and feeding the substrate (a); and a supporting roller (17) for the substrate, which is provided at the lower end of the roller section and driven by a drive device (15, 25, 16, 26). ) the substrate (a) consisting of at least
is transported rightward at a predetermined speed by a transporting body.

During this conveyance, a filter (
F) substantially removes dust, etc., and a predetermined copper etching solution supplied via a pressure regulating valve is sprayed.
Etching is performed within the range of the conditions described above.

Although only the etching device part is shown in the drawings above, as described later, it is usually preferable to remove the etching solution immediately after the etching is completed (immediately after spraying) or to add means for stopping the etching ability of the etching solution. In the present invention, after etching is completed, it is preferable to carry out neutralization, washing with water or cleaning, rust prevention treatment, drying, etc. in a series of lines as one continuous device. Furthermore, it is possible to perform etching in multiple stages, and to insert a reversing mechanism between the stages, as appropriate.

In addition, in order to obtain a copper foil of a predetermined thickness by etching, the etching liquid must be used under the predetermined etching conditions (type and concentration of the etching liquid, temperature, spray pressure, substrate (a)).
A method is used in which the etching speed is measured under the following conditions (e.g., feeding speed), the etching time is set, and the etching solution is managed to maintain this etching speed. For example, when removing copper of the same thickness from both sides, a method is used in which the spray pressure on both the left and right sides is the same and etching is performed for a predetermined period of time. In addition, in order to obtain copper foils with different predetermined thicknesses, the left and right spray pressures or the number of sprays used, especially the number of sprays, are adjusted to set the etching speed of the left and right surfaces to the desired speed ratio within the desired speed range. method can be used.

Another method is to use a double-sided copper-clad circuit board to be used for etching, such as one with 35p electrolytic copper foil on one side and 18p electrolytic copper foil on the other side, and etching both sides at the same rate; A method in which a removable protective film such as a plastic film is formed on the entire surface or especially around one side using electrolytic copper foil, and etching is performed on only one side - a method in which a double-sided copper-clad circuit board is stood vertically, etc. Illustrated. Furthermore, the method of completely removing the copper foil on one side and leaving a thin copper foil of the desired thickness on the other side is the method of etching the side surface from which the copper foil has been completely removed, in the method for forming copper foils of different predetermined thicknesses described above. By setting the speed even higher than above. In addition, cleaning refers to neutralization, acid washing,
Known methods for removing impurities such as washing with water or hot water may be used, and these should be selected appropriately taking into account the copper etching solution used, its stabilizer, and other components. However, washing with a weakly acidic aqueous solution or water at room temperature or under heating After that, it was pickled and neutralized with an aqueous solution of 1 to 5 wt% of sodium carbonate at 20 to 50°C, and a well-known copper rust inhibitor was added as a rust preventive at 0.01 to 1 wt%, as appropriate. It is preferable to perform the treatment at 20 to 50°C using an aqueous solution containing a surfactant or the like.

In addition, after the rust prevention treatment, heat-removable resins such as polyethylene, polypropylene, ethylene-propylene resin, ethylene-vinyl acetate resin, vinylidene chloride, polyacrylate copolymer, 1,2-polybutadiene resin, polyester resin, etc. Plastic resin films and photoresist films; General-purpose solvent-soluble resins such as paraffin wax, polyethylene wax, rosin, and low molecular weight polystyrene: Copper foil surfaces can also be covered by pressure bonding photoresist resin liquid, etc. preferable.

Moreover, in the above, the thin copper foil-clad circuit board taken out usually has a hole and an end portion for fixing the frame. If it is necessary to remove the holes, edges, etc., these parts are removed to produce a product.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples. Note that the thickness of the copper foil was measured using an eddy current method.

Example 1 We prepared 100 glass cloth-based epoxy resin laminates, each 700 x 1020 mm thick with a thickness of 0.1mm and coated with copper foil on both sides having an average thickness of 15ρ treated with a low profile on one side. ~2 Thin copper foil-clad circuit boards with a thickness of 9 mm are fabricated using the etching device shown in Figure 2, which is further connected to a water washing or dilute acid cleaning section, a neutralization processing section, a rust prevention processing section, and a drying section at the rear. was manufactured.

The etching solution and etching conditions were set as follows.

Next, spray washing with a sulfuric acid aqueous solution with a concentration of 0.01 to 0.05% at room temperature, spray neutralization treatment with a 5% Na2CO3 aqueous solution at room temperature, and spraying with a benzotriazole aqueous solution with a concentration of 0.3% at 40 ° C. Antirust treated, 100%
Dry with hot air at ℃.

For all 100 thin copper clad boards obtained, the copper foil thickness was measured at any point within 25 rectangles obtained by dividing the thickness of the copper foil into 5 equal parts vertically and horizontally, and the average thickness was 8.
．． 9mm, maximum 9.3-1 minimum 8.6mm, the variation with respect to the average thickness is ±0.44, the variation with respect to the desired thickness is ±0.4Jj2a, and 95% of the measurement points are 8.7 to 9 The surface roughness was in the range of 2.0 to 3.0 degrees.

Furthermore, the obtained thin copper clad plate was heated at 25°C and 60%RH for 30 minutes.
Although it was kept for a long time, no rust was observed.

Example 2 The conditions were the same as in Example 1 except that the conditions were used to manufacture a thin copper foil-clad circuit board with a thickness of 5 J and aa.

The etching solution and etching conditions were set as follows.

For all 100 thin copper clad boards obtained, the copper foil thickness was measured at any point within 25 rectangles obtained by dividing the copper foil thickness into 5 equal parts vertically and horizontally, and the average thickness was 5.
．． The maximum thickness is 5.4p, the minimum is 4.6p, the variation with respect to the average thickness is ±0.5p, the variation with respect to the desired thickness is ±0.4p, and 95% of the measurement points are 4.7 to 5. The surface roughness was in the range of 1.8 to 2.6 mm.

Furthermore, the obtained thin copper clad plate was heated at 25°C and 60%RH for 30 minutes.
Although it was kept for a long time, no rust was observed.

[Operation and effects of the invention]

From the above detailed description of the invention and examples, it is clear that according to the vertical etching method of the present invention, the difference in the amount of etching due to differences in the left and right sides or the top and bottom positions of the substrate is extremely small, and moreover, it can be stably etched continuously for a large number of substrates. It is understood that etching is possible. As a result, it is possible to easily produce a thin copper foil-clad board with a copper foil thickness accuracy that is equal to or better than that of conventional ultra-thin copper foil.

Furthermore, since the present invention has excellent thickness accuracy as described above, it is possible to manufacture ultra-thin copper-clad laminates, which could only be manufactured by vapor deposition, etc. in the past, and has industrial advantages. The significance is extremely great.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a vertical etching apparatus used in the present invention, and FIG. 2 is a side view of the same. The symbols and numbers in the figure are respectively 10.20: etching tank, 11, 21: drive shaft, 12, 22: drive gear,
13, 23: Roller drive gear, 14.24 + roller, 15, 25: drive shaft, 16.26 + drive gear,
17: Support roller, 18.28 Varnish spray nozzle, P
: pump, F: filter. Patent applicant Mitsubishi Gas Chemical Co., Ltd. agent (9070) Patent attorney Sadafumi Kobori Engraving of drawings Figure 1 9, Figure 2 Procedural amendment (method) % formula % ■, Indication of case 1990 Patent Application No. 325481 2. Name of the invention: Method for manufacturing a thin copper foil-clad circuit board. 3.4I Applicant Address (■100) 2-5-2 Marunouchi, Chiyoda-ku, Tokyo Name (446) Mitsubishi Gas Chemical Co., Ltd. Representative Reiji Kajo 4, Agent Residence (■100) Chiyoda-ku, Tokyo Marunouchi 2-5-2-5, date of amendment order: February 25, 1991 (shipment date: 32-yi-mi, 1991)
Brain) 6. Drawings to be corrected. 7. Contents of the amendment As shown in the attached sheet, (-1-throat~

Claims (1)

[Claims] 1. Thin copper, in which the entire surface of a copper foil-clad circuit board (a) manufactured from a copper foil with an average thickness of 12 μm or more and an electrical insulator is etched using a copper etching solution while being conveyed upright. A method for manufacturing a foil-clad circuit board, which includes a feeding drive tool (1) provided at the upper end of the foil-clad circuit board along the conveyance direction, and a feed drive tool (1) that is driven by the drive tool (1), and the film is almost completely covered on both left and right sides below the feeding drive tool (1). A roller section that sandwiches and conveys the substrate (a), comprising a large number of rollers (4) arranged opposite to each other with their axes in the vertical direction, each along the conveyance direction and arranged on the axis; (4) Support roller (7) for the substrate provided at the lower end
and a nozzle part (B) comprising a large number of spray nozzles (8) provided on both left and right sides of the substrate (a) along the transport direction. Insert the substrate (a) and
．． Etch the entire surface of the copper foil at a rate of 4 μm/sec, leaving 10 to 80% of the original copper foil thickness, and keep the variation in the thickness of the remaining copper foil within ±1.0 μm from the desired thickness. A method for manufacturing copper foil-clad circuit boards. 2. A drive shaft (5) is also provided beside the support roller (7) along the conveyance direction, and the support roller (7) is driven in the conveyance direction at the same feed speed as the roller (4). 2. The method for producing a thin copper foil-clad circuit board according to claim 1, wherein the method is driven by a shaft (5). 3. The thin copper foil-clad circuit board according to claim 1, characterized in that two etching zones having the nozzle portion (B) are provided, and an inverted portion (C) of the substrate (a) is provided in the middle thereof. manufacturing method. 4. The method for producing a thin copper foil-clad circuit board according to claim 1, wherein the copper etching solution supplied to the spray nozzle (8) is filtered in advance. 5 The etching has an etching rate of 0.01 to 03μ
2. The method for manufacturing a thin copper foil-clad circuit board according to claim 1, wherein the spray pressure is in the range of 0.3 to 1.3 kg/cm^2. 6 The copper etching solution contains 1.5 to 4 w/v of hydrogen peroxide.
%, sulfuric acid 3-7 w/v%, copper 10-100 g/l, hydrogen peroxide, sulfuric acid and copper concentrations are controlled within ±1.0% of the predetermined concentration, and the temperature is ±1.0% at 25-60°C. 0deg.
6. The method for producing a thin copper foil-clad circuit board according to claim 5, wherein 7 The copper etching solution contains 0.0% alcohol as an auxiliary agent.
7. The method for producing a thin copper foil-clad circuit board according to claim 6, wherein the content is 1 to 5 w/v%. 8 The copper etching solution contains 0.25 to 3 mo of cupric chloride.
l/l, hydrochloric acid 1 to 5 mol/l, and the hydrochloric acid concentration is controlled within ±0.3 mol/l of the predetermined concentration, and the temperature is 25 to 5 mol/l.
±5.0deg. at 55°C. 6. The method for producing a thin copper foil-clad circuit board according to claim 5, wherein